Persistent spatial inequalities in contraceptive use in Nigeria: a Bayesian spatio-temporal model evidence from demographic health survey data from 2003 to 2024

Contraceptive use remains unevenly distributed across Nigeria despite ongoing reproductive health interventions. This study assessed the spatio-temporal distribution and determinants of contraceptive use among women of reproductive age in Nigeria. Data from the 2003, 2008, 2013, 2018, and 2024 Nigeria Demographic and Health Surveys involving 127,865 women aged 15–49 years were analyzed. Bayesian spatio-temporal conditional autoregressive models were fitted using the Integrated Nested Laplace Approximation (INLA) approach. Spatial, temporal, and nonlinear effects were modeled, and posterior exceedance probabilities were estimated. Overall prevalence of contraceptive use increased from 14.5% in 2003 to 20.7% in 2024, with a pooled prevalence of 16.0%. Contraceptive use was significantly associated with education ( \(\:{\chi\:}^{2}\) = 13192.019, p < 0.001) also wealth index, residence, marital status, and region were all significantly associated with increase prevalence of contraceptive use. Women with higher education had over four times higher odds of contraceptive use (OR = 4.10; 95%CI: 3.79–4.43), while women from the richest households had significantly higher odds of use (OR = 2.78; 95% CI: 2.55–3.03). Significant spatial heterogeneity persisted across states (σ = 0.54), with southern states showing higher exceedance probabilities of contraceptive prevalence above the national average. Although contraceptive use improved over time, substantial spatial and socioeconomic inequalities remain across Nigeria. Targeted reproductive health interventions should prioritize underserved northern and rural communities to reduce persistent disparities in contraceptive use.